1. Field of the Invention
The present invention relates to an automatic vehicle brake system for automatically applying braking force when the actual vehicle speed is determined to be higher than a proper or appropriate vehicle travelling speed. The actual vehicle speed is compared with the proper vehicle travelling speed to ensure that the vehicle successively passes a forward curve or otherwise properly follows a roadway.
2. Description of the Related Art
An automatic brake system of the sort mentioned above for a vehicle is disclosed in Japanese Patent Application Laid-open No. 6-281471. The proper vehicle travelling speed which allows a vehicle to successfully negotiate a curve varies with the friction coefficient of the road surface. When the road surface is slippery, the proper vehicle travelling speed is low because marginal lateral acceleration decreases at the time of passing the curve. When the slippery road surface is detected, application of the brake is started in good time to lower the vehicle speed sufficiently when the vehicle enters the curve. When the slippery condition of the road surface is detected to be greater than the actual condition of the road surface through erroneous detection due to limitations in slippery or friction detection accuracy, automatic braking may be started well in advance of the curve, and the vehicle speed may be excessively decelerated when the vehicle enters the curve. The driver may be disturbed by this unexpected vehicle operating characteristic.